Worms Blast is a puzzle game similar in concept to Puzzle Bobble, with several important distinctions and gameplay features taken from Worms games. Instead of releasing and matching bubbles, the player has to color blocks on a hexagonal grid. Unlike most Bust-A-Move variants, the player character can move right and left, sailing in a boat. Various weapons, such as bazooka, grenades, dynamite, and others, can be used to fire at the blocks, coloring them on impact. Like in the main, artillery-based Worms games, holding down the fire button increases the power of the weapon, affecting the distance it travels.

If the player hits a block that is either the same color as the missile fired, that block and any other same-colored blocks adjacent to it will be destroyed. Differently-colored blocks will not be affected by shooting at them; however, if they are held solely by a group of blocks of the same color, they will fall into the water when that group disappears. Blocks with rainbows on them can count as any color. Unlike Puzzle Bobble, there are no walls in single-player mode. If the player aims the weapon outside of the screen, a heavy object might fall on the player-controlled boat, damaging it.

The game's main mode is called "Puzzle mode": the player completes various stages, the goal being different in each (e.g. shooting down certain forms of blocks, avoiding hostile blocks that move around the screen, etc.). Beside this mode, the game features a single-player tournament mode with high scores, as well as a variety of multiplayer modes. The action component is particularly noticeable in this mode, since the walls between the areas will periodically open, allowing players to use this opportunity to shoot at each other's boats.